The present invention relates generally to optical fiber systems, and more specifically the invention pertains to a transparent optical node (TON) structure for use in a two-connected optical packet switching architecture.
Packet or cell switching in communications is of current interest due to the great increase of signal transmission rates. As these transmission rates increase, files of information no longer occupy the full physical distance between source and destination nodes during transmission making circuit-switched techniques inefficient compared to a self-routing packet switched technique. To take advantage of the ultra-fast rates of optical interconnects, TON structures are required to avoid full optical to electronic to optical conversion of the signal at every node in the network. This conversion process reduces the throughput rates to that of current state-of the art electronics.
The task of providing transparent optical node interconnects for fiber optic communication systems is alleviated, to some extent, by the systems disclosed in the following U.S. Patents, the disclosures of which are incorporated herein by reference:
U.S. Pat. No. 5,284,422 issued to Handa;
U.S. Pat. No. 5,241,409 issued to Hill;
U.S. Pat. No. 5,223,972 issued to Nishimura;
U.S. Pat. No. 5,222,163 issued to Handa;
U.S. Pat. No. 5,109,444 issued to Handa;
U.S. Pat. No. 4,503,532 issued to Page; and
U.S. Pat. No. 4,468,085 issued to Papuchon.
The above cited patents all describe optical node structures for fiber optical communication systems. Latency in transit through an interconnect remains a problem for these systems. As the size of a network grows, the latency increases with the average number of hops a packet makes in transit in the network. For a ring topology interconnect, this latency increases linearly with the number of nodes N while in a two-connected topology such as Shuffle-net the latency increases logrithmically with N. A two-connected topology increases the physical complexity of the node structure, requiring routing and add/drop multiplexing for both inputs to both outputs of the node. One of the problems with ultra-fast transmission rates in packet switching is the necessity to obtain pertinent header information out of the packet's optical bit stream at every node the packet encounters. The present invention is intended to satisfy this need.